15781
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 22
- Digital Root
- 4
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 16192
- Proper Divisor Sum (Aliquot Sum)
- 411
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 15372
- Möbius Function
- 1
- Radical
- 15781
- Omega Function (Ω)
- 2
- Little Omega Function (ω)
- 2
Special
- Factorial
- no
- Catalan Number
- no
- Bell Number
- no
- Motzkin Number
- no
- Primorial
- no
Figurate Numbers
- Fibonacci Number
- no
- Triangular Number
- no
- Perfect Square
- no
- Perfect Cube
- no
- Pentagonal Number
- no
- Hexagonal Number
- no
- Lucas Number
- no
- Tetrahedral Number
- no
- Pell Number
- no
- Tribonacci Number
- no
- Pronic Number
- no
Recreational
- Happy Number
- no
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 102
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- yes
- Squarefree Number
- yes
- Prime Power
- no
- Prime Factorization
- no
- Twin Prime
- no
- Mersenne Prime
- no
- Sophie Germain Prime
- no
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 82 ones.at n=17A031850
- Number of rooted compound windmills with n nodes and leaves of 2 colors with no symmetries.at n=9A032172
- Sums of 5 distinct powers of 5.at n=6A038477
- Numerators of continued fraction convergents to sqrt(141).at n=6A041258
- Numbers k such that 299*2^k + 1 is prime.at n=27A053366
- Inverse of coefficient array of orthogonal polynomials P(n,x)=(x-n)*P(n-1,x)-(2n-3)*P(n-2,x), P(0,x)=1,P(1,x)=x-1.at n=40A178125
- Number of partitions into a triangular number of parts.at n=44A178927
- a(n) = 25*n^2 + 15*n + 1021.at n=24A214732
- Smallest positive multiple of n whose base-5 representation contains only 0's and 1's.at n=42A244956
- Partial sums of A256970.at n=32A256971
- a(n) = (n+1)*Sum_{k=1..n} binomial(n-1,k-1)*binomial(n+2*k+2,k+1)/(n+k+2).at n=4A262410
- Array read by antidiagonals: T(m,n) = number of irredundant sets in the lattice (rook) graph K_m X K_n.at n=39A290818
- Array read by antidiagonals: T(m,n) = number of irredundant sets in the lattice (rook) graph K_m X K_n.at n=41A290818